I found some sample code like below, for trying to customize a scrollbar color:
HBRUSH CMainFrame::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor) { HBRUSH hbr = CFrameWnd::OnCtlColor(pDC, pWnd, nCtlColor); if(nCtlColor==CTLCOLOR_SCROLLBAR) return m_brColor; return hbr; } I found that the following code does not work:
procedure TForm1.WMCTLColor(var msg: TWMCTLCOLOR); message WM_CTLCOLOR; How can I do it in Delphi?
There's no WM_CTLCOLOR message in the native api. Instead you can use CN_CTLCOLORSCROLLBAR control notification, which is send to child controls by the VCL in response to the API's WM_CTLCOLORSCROLLBAR.
type TScrollBar = class(TScrollBar) protected procedure WMCtlColor(var Message: TWMCtlColorScrollbar); message CN_CTLCOLORSCROLLBAR; end; procedure TScrollBar.WMCtlColor(var Message: TWMCtlColor); begin Message.Result := CreateSolidBrush(RGB(255, 255, 0)); end;
Or, if you don't want to derive a new control, provided the scrollbar is placed on the form:
TForm1 = class(TForm) ... protected procedure WMCtlColorScrollbar(var Message: TWMCtlColorScrollbar); message WM_CTLCOLORSCROLLBAR; ... end; procedure TForm1.WMCtlColorScrollbar(var Message: TWMCtlColorScrollbar); begin if Message.ChildWnd = ScrollBar1.Handle then Message.Result := CreateSolidBrush(RGB(255, 255, 0)); end; 
WS_VSCROLL and WS_HSCROLL styles, there're no separate scrollbar controls in the memo. Neither the code you gave in the question, or the code in this answer will work for such a case.This improvement avoids the memory leak by the repeated calling of CreateSolidBrush()
{ TMyScrollBar } //****************************************************************************** constructor TMyScrollBar.Create(AOwner: TComponent); begin inherited; FHBrush := CreateSolidBrush(ColorToRGB(FBackColor)); end; //****************************************************************************** destructor TMyScrollBar.Destroy; begin DeleteObject(FHBrush); inherited; end; //****************************************************************************** procedure TMyScrollBar.SetBackColor(const Value: Tcolor); begin FBackColor := Value; DeleteObject(FHBrush); FHBrush := CreateSolidBrush(ColorToRGB(FBackColor)); end; //****************************************************************************** procedure TMyScrollBar.WMCtlColor(var Message: TWMCtlColorScrollbar); begin Message.Result := FHBrush; end; 